Apparatus and methods for regulated voltage

ABSTRACT

An electronic system according to various aspects of the present invention includes a memory and a supply regulation circuit having a regulated output to provide a selected voltage level. In one embodiment, the supply regulation circuit includes a reference voltage circuit connected to the supply and configured to receive a first voltage and a second voltage and provide a reference voltage and a control circuit connected to the reference voltage and configured to control the regulated voltage according to the reference voltage. The supply regulation circuit also includes an adjustment circuit controlled by the control circuit and configured to adjust the regulated voltage according to the reference voltage. The supply regulation circuit may also include a compensator circuit to provide additional adjustment to the regulated voltage.

FIELD OF INVENTION

[0001] The present invention generally relates to electronic circuits.

BACKGROUND OF THE INVENTION

[0002] Many electronic systems use multiple voltage levels in the samesystem, and often in the same component. Electronic systems use variousvoltage levels to drive signals and promote particular operatingcharacteristics for a circuit. For example, a memory chip may requireseveral different voltage levels to operate, such as a main supplyvoltage, a main supply ground, a bulk voltage, and a negative word linevoltage.

[0003] Many power supply schemes have been developed for accommodatingthe different voltage levels. One possible configuration is to minimizethe number of voltage levels by using identical voltage levels fordifferent functions. For example, a memory may be configured to use thesame voltage level for the bulk voltage V_(BB) and the negative wordvoltage V_(NEG). Using identical voltage levels for different signals,however, reduces flexibility and tends to inhibit optimal operation.

[0004] An alternative solution is to provide a dedicated circuitincluding a charge pump for each voltage level to provide the requisitepower to the system. These systems are relatively expensive, however,for each dedicated circuit in the system requires additional materials,fabrication, testing, chip space, and design. Further, using dedicatedcircuits for each voltage level adds complexity. For example, thevarious voltage level supply circuits may require activation in aselected sequence to avoid latchup problems.

SUMMARY OF THE INVENTION

[0005] An electronic system according to various aspects of the presentinvention includes memory and a supply regulation circuit having aregulated output to provide a selected voltage level. In one embodiment,the supply regulation circuit includes a reference voltage circuitconfigured provide a reference voltage. The supply regulation circuitalso includes a control circuit connected to the reference voltage andconfigured to control the regulated voltage according to the referencevoltage. In addition, the supply regulation circuit includes anadjustment circuit controlled by the control circuit and configured toadjust the regulated voltage according to the reference voltage. Thesupply regulation circuit may also include a compensator circuit toprovide additional adjustment or maintenance to the regulated voltage.

BRIEF DESCRIPTION OF THE DRAWING

[0006] Aspects of the present invention are disclosed in thenon-limiting embodiments described in the specification and the claims,in conjunction with the accompanying figures, wherein like numeralsdesignate like elements:

[0007]FIG. 1 is a block diagram of an electronic system according tovarious aspects of the present invention;

[0008]FIG. 2 is a block diagram of an exemplary supply and a memorysystem;

[0009]FIG. 3 is a block diagram of an exemplary supply regulationcircuit;

[0010]FIG. 4 is a schematic diagram of an exemplary supply regulationcircuit;

[0011]FIG. 5 is a schematic diagram of an exemplary reference voltagecircuit;

[0012]FIG. 6 is a schematic diagram of an exemplary supply regulationcircuit having a compensation circuit including a current source;

[0013]FIG. 7 is a schematic diagram of an exemplary supply regulationcircuit having a compensation circuit including a second differentialamplifier and an adjustable impedance; and

[0014]FIG. 8 is a schematic diagram of an exemplary integrated controlcircuit and adjustment circuit.

[0015] Elements in the figures are illustrated for simplicity andclarity and have not necessarily been drawn to scale. For example, thedimensions of some of the elements in the figures may be exaggeratedrelative to other elements to improve understanding of the embodimentsof the present invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0016] Various aspects and features of the present invention may bedescribed in terms of functional components and steps. Such functionalcomponents and steps may be realized by any number of elements and/orsteps configured to perform the specified functions. For example, thepresent methods and apparatus may employ electronic, signaling, andlogic elements, like impedances, transistors, operational amplifiers,voltage supplies, and current sources, which may carry out a variety offunctions in various embodiments, applications, and environments. Inaddition, the present methods and apparatus may be practiced inconjunction with any number of procedures and systems, and the apparatusand methods described are merely exemplary applications for theinvention. Further, the methods and apparatus may employ any appropriatetechniques, conventional or otherwise, for placement, use,manufacturing, and the like.

[0017] An electronic system according to various aspects of the presentinvention includes a plurality of components operating in conjunctionwith a supply regulation circuit. The components may comprise anycomponents using a supply regulation circuit, such as multipleintegrated circuits and electrical components on a single board, variouselements in a single integrated circuit, various components of acomputer system, or any other components. For example, referring to FIG.1, an exemplary electronic system 100 suitably comprises a computerhaving a processor 110, a supply 112, and a memory system 114. Theprocessor 110 controls the electronic system 100, such as in accordancewith a program. The processor 110 may comprise any controlling element,for example a conventional central processing unit, such as an IntelPentium processor or an Advanced Micro Devices Athlon processor.

[0018] The supply 112 provides power to the various components of theelectronic system 100, including the processor 110 and the memory system114. The supply 112 may comprise any source of power for the electronicsystem 100, such as a conventional electric power supply, a charge pump,and/or other power supplies. In the present embodiment, the supply 112is connected to the processor 110 and is configured to supply at leasttwo voltage levels. Although the present embodiment includes theprocessor 110, the supply 112, and the memory system 114, the electronicsystem 100 may include any suitable components.

[0019] The memory system 114 stores information for subsequentretrieval. The memory system 114 may comprise any appropriate memory,memory system, or storage device or system. The memory system 114 maycomprise, be replaced by, or be supplemented by any component or systemdrawing power from the supply 112. The memory system 114 is suitablyconnected to the processor 110 and configured to provide information tothe processor 110. For example, referring to FIG. 2, the memory system114 of the present embodiment suitably comprises a memory 210 and asupply regulation circuit 212. The memory 210 comprises any suitablesystem for storing data for later retrieval, such as a memory subsystemincluding a memory controller, multiple memory chips, and associatedlogic and circuitry. In the present embodiment, the memory 210 comprisesan SDRAM, such as an SDRAM available from Micron Technology, Inc. Thememory 210 suitably includes multiple word lines and bit lines used tostore information at selected addresses in the memory 210.

[0020] The supply regulation circuit 212 controls the supply levels toone or more components of the electronic system 100, such as the memory210. In the present embodiment, the supply regulation circuit 212 isintegrated into the memory 210, though the supply regulation circuit 212may be integrated into other components of the memory 210 or implementedas a separate circuit. The supply regulation circuit 212 according tovarious aspects of the present invention provides selected voltagelevels to the memory 210. In particular, the supply regulation circuit212 is connected to the supply 112 to receive power and may beconfigured to generate, monitor, and regulate one or more particularvoltages for the memory 210. The supply regulation circuit 212 maycomprise any suitable supply regulation circuit, such as a voltagecontrol circuit, current control circuit, or any other supply regulationcircuit or suitable combination of circuits.

[0021] In the present embodiment, the supply regulation circuit 212 isconfigured to generate a negative word line voltage V_(NEG) to supply anegative signal to one or more word lines of the memory 210. The supplyregulation circuit 212 may be configured in any suitable manner toprovide the negative word line voltage V_(NEG). The supply regulationcircuit 212 may be configured to provide and regulate selected voltagesand/or currents according to any criteria and in any suitable manner.For example, referring to FIG. 3, a supply regulation circuit 212according to various aspects of the present invention is configured toselectively provide at least one regulated voltage and/or current to theword lines of the memory 210. The supply regulation circuit 212 suitablycomprises a reference voltage circuit 310; a control circuit 312; and anadjustment circuit 314. The reference voltage circuit 310 is suitablyconnected to the supply 112 and configured to provide a controlreference voltage. The control circuit 312 is suitably connected to thereference voltage circuit 310 and configured to control the regulatedvoltage according to the control reference voltage. Further, theadjustment circuit 314 is suitably controlled by the control circuit 312and configured to adjust the regulated voltage according to the signalsreceived from the control circuit.

[0022] More particularly, the reference voltage circuit 310 generatesone or more control reference voltages, such as a control referencevoltage for the negative word line voltage V_(NEG). In the presentembodiment, the control reference voltage may comprise any suitablevoltage or other signal to be used as a target voltage by anothercomponent. The reference voltage circuit 310 may be configured in anysuitable manner to generate the control reference voltages. For example,referring to FIG. 4, the reference voltage circuit 310 is connected to afirst voltage and a second voltage to generate the control referencevoltage between the first and second voltages. The reference voltagecircuit 310 suitably comprises a voltage divider circuit having a firstterminal connected to, for example, a main ground V_(SS) from the supply112 and a second terminal connected to, for example, a bulk voltageV_(BB), also suitably generated by the supply 112. At least twoimpedances 410, 412 form the voltage divider. In the present embodiment,the impedances 410, 412 comprise conventional resistors. Alternatively,the impedances 410, 412 may comprise variable resistors,resistive-capacitive elements, transistors, or any other appropriateelements for generating the desired control reference voltage. Further,the first and second voltages may be any appropriate voltages or othersignals from which the control reference voltage may be derived.

[0023] In another embodiment, the reference voltage circuit 310 may beconfigured to generate multiple control reference voltages. For example,referring to FIG. 5, a voltage divider may be configured having multipleimpedances 510 and multiple taps 512 to generate multiple controlreference voltages. The multiple control reference voltages, however,may be generated by any suitable system for generating multiplereference voltages. Any number of control reference voltages may begenerated for use by the memory 210 and/or other components of theelectronic system 100. Further, the reference voltage circuit 310 may beconfigured in any suitable manner to connect the regulated voltage toground or another potential, for example in response to a test mode thatmay require discharging a relatively large load from the memory 210.

[0024] In addition, the reference voltage circuit 310 may include abuffer, for example between the supply 112 and one or more of the supplyterminals of the reference voltage circuit 310. The buffer may beincluded or omitted according to the configuration of the supplyregulation circuit 212. For example, if the supply 112 comprises a highimpedance node, the buffer may be included to provide a lower impedancesource for the supply voltage.

[0025] The control circuit 312 controls the regulated voltage accordingto the control reference voltage. In one embodiment, the control circuit312 compares the regulated voltage to at least one of the controlreference voltages. The control circuit 312 also suitably controls theadjustment circuit 314, for example by generating a control signalprovided to the adjustment circuit 314.

[0026] The control circuit 312 may comprise any suitable circuit forcontrolling the adjustment circuit or providing the regulated voltageaccording to the control reference voltage circuit. Referring again toFIG. 4, the control circuit 312 of the present embodiment comprises adifferential amplifier 414 having an inverting input connected to thecontrol reference voltage and a noninverting input connected to theregulated voltage. The differential amplifier 414 generates the controlsignal, such as a differential signal proportional to the differencebetween the control reference voltage and the regulated voltage, whichis suitably provided to the adjustment circuit 314.

[0027] Referring to FIG. 8, an alternative embodiment of a controlcircuit 312 provides the regulated voltage directly with an integratedadjustment circuit 314. The control circuit 312 provides a signal at thelevel of the control reference voltage to maintain the output voltage atthe level designated by the control reference voltage. For example, thecontrol circuit 312 suitably comprises a substantially unity (eitherinverting or noninverting) gain amplifier, to drive the adjustmentcircuit 314. In the present embodiment, the control circuit 312 isimplemented as an inverting operational amplifier having a gain ofapproximately 1 or −1. In particular, the operational amplifier has anoninverting input connected to ground and an inverting input connectedto the reference voltage circuit 310 via an input resistor. Theinverting input is also connected to the output of the operationalamplifier via a feedback resistor having a substantially identicalresistance as the input resistor.

[0028] The adjustment circuit 314 is controlled by the control circuit312 and is configured to generate the regulated voltage using anothervoltage and adjust the regulated voltage according to the controlsignal. The adjustment circuit 314 may be configured in any suitablemanner to generate the regulated voltage and adjust the regulatedvoltage according to the control reference voltage. For example,referring again to FIG. 4, the adjustment circuit 314 suitably comprisesan adjustable impedance, such as an n-channel insulated gate transistor416. If appropriate, the transistor 416 may be supplementally implantedto raise its threshold voltage such that the transistor 416 is off whenthe gate voltage is at the lowest voltage supplied by the controlcircuit, such as ground V_(SS). The transistor 416 has a controlterminal for adjusting the impedance of the transistor, such as a gate,connected to the control circuit 312 to receive the control signal. Asupply terminal, such as the drain of the transistor 416, is connectedto a supply voltage from which the word line supply voltage V_(NEG) isdrawn, such as the bulk voltage V_(BB). The regulated voltage issuitably provided at the source of the transistor 416. In the presentembodiment, the negative word line voltage V_(NEG) voltage level isselectively connected to the word lines of the memory 210. Theadjustment circuit 314 may thus adjust the regulated voltage V_(NEG) byvarying the impedance of the transistor 416.

[0029] In the alternative embodiment, the adjustment circuit 314 may beomitted or integrated into an amplifier 810 (FIG. 8). The amplifier 810is suitably configured to automatically compensate for changes incurrent or voltage at its output to maintain a substantially constantvoltage. The adjustment circuit 314 is integrated into the amplifier810. Accordingly, the output of the amplifier 810 may be used as theoutput V_(NEG) of the supply regulation circuit 212.

[0030] In operation, the negative word line voltage V_(NEG) isselectively connected to one or more word lines of the memory 210.Consequently, the voltage applied to the negative word line voltageV_(NEG) varies as charged word lines are connected to the negative wordline voltage V_(NEG) following memory 210 accesses. As the negative wordline voltage V_(NEG) changes, the control circuit 312 compares thecurrent negative word line voltage V_(NEG) to the control referencevoltage. If the current negative word line voltage V_(NEG) is too high,the control circuit 312 adjusts the control signal, for example toreduce the impedance of the transistor 416. In particular, thedifferential amplifier 414 generates a differential signal having anamplitude corresponding to the magnitude of the difference between thecontrol reference voltage and the negative word line voltage V_(NEG).The differential signal is provided to the transistor 416 of theadjustment circuit 314, which reduces the impedance of the transistor416. As a result, the negative word line voltage V_(NEG) is pulled lowertowards the bulk voltage V_(BB), thus returning the negative word linevoltage V_(NEG) to the proper voltage level. Similarly, if the negativeword line voltage V_(NEG) is too low, the control circuit 312 adjuststhe control signal to increase the impedance of the transistor 416. Theadjustable impedance of the transistor 416 tends to drive the negativeword line voltage V_(NEG) towards the control reference voltage, thusmaintaining the desired regulated voltage for, for example, the negativeword line voltage or other desired signal. In embodiments having omittedor integrated adjustment circuits 314, the control circuit 312 adjuststhe output signal of the control circuit 312 to maintain the desiredvoltage according to the control reference voltage.

[0031] Thus, a supply regulation circuit 212 according to the presentembodiment provides a negative word line voltage V_(NEG) by maintaininga signal between the bulk voltage V_(BB) and ground. The bulk voltageV_(BB) supply provides all of the required current. The adjustmentcircuit 314 facilitates siphoning any required current from the bulkvoltage V_(BB) supply. Consequently, a single pump of adequate capacitymay supply both the bulk voltage V_(BB) and the negative word linevoltage V_(NEG). In this embodiment, if either load connected to thebulk voltage V_(BB) and the negative word voltage V_(NEG) exceeds normaloperating conditions, the single pump can supply the necessary power.Further, the supply regulation circuit 212 according to the presentembodiment prevents the negative word voltage V_(NEG) from becoming morenegative than the bulk voltage V_(BB), which might otherwise lead to alatchup problem.

[0032] A supply regulation circuit according to various aspects of thepresent invention may also comprise a compensator circuit to compensatefor any extra current or other operational requirement of the regulatedvoltage. For example, the compensator circuit may be connected to thenegative word voltage V_(NEG) to compensate for leakage current in thetransistor 416. The compensator circuit may be configured in anysuitable manner to compensate for the leakage current.

[0033] For example, referring to FIG. 6, the compensator circuit mayinclude a current source 610 connected to the source of the transistor416. The current source 610 may provide a relatively low current to theregulated voltage to compensate for current lost as leakage or stand-bycurrent. In the present embodiment, the current source 610 inhibits thenegative word voltage V_(NEG) from becoming more negative than thecontrol reference voltage. The current source 610 may be implemented inany suitable manner, such as using a conventional current mirror circuitto maintain a desired current through the transistor 416.

[0034] In an alternative embodiment, the compensator circuit may beconfigured to compare the regulated voltage to the reference voltage andcompensate if the regulated voltage is too low. For example, referringto FIG. 7, an alternative compensator circuit according to variousaspects of the present invention suitably comprises a seconddifferential amplifier 710 and a second transistor 712. The seconddifferential amplifier 710 has a noninverting input connected to thecontrol reference voltage and an inverting input connected to thenegative word line voltage V_(NEG). Like the first differentialamplifier 414, the second differential amplifier 710 generates adifferential signal proportional to the difference between the controlreference voltage and the negative word line voltage V_(NEG), which issuitably provided to a second impedance, such as the n-channeltransistor 712.

[0035] The second transistor 712 is suitably configured to modulate theimpedance between a more positive voltage level, such as ground, and thenegative word line voltage V_(NEG) according to the second differentialsignal generated by the second differential amplifier 710. In thepresent embodiment, the gate of the second transistor 712 is connectedto the second differential output, and the source and drain of thesecond transistor 712 are suitably connected to ground and the source ofthe first transistor 416, respectively. The second transistor 712 may beconfigured to exhibit additional resistance or may be connected to anadditional resistor to increase the resistance of the compensationcircuit. The negative word line voltage V_(NEG) is provided at the nodebetween the first impedance 416 and the second impedance 712. Thus, thefirst differential amplifier and transistor pair 414, 416 tends to pullthe negative word line voltage V_(NEG) to the control reference voltageif the negative word line voltage is too high, and the seconddifferential amplifier and transistor pair 710, 712 tends to pull thenegative word line voltage V_(NEG) to the control reference voltage ifthe regulated voltage is too low.

[0036] The present invention is described with reference to variouspreferred embodiments. However, changes and modifications may be made tovarious exemplary embodiments without departing from the scope of thepresent invention. These and other changes or modifications are intendedto be included within the scope of the present invention as set forth inthe appended claims.

1. An electronic system, comprising: a processor; a supply connected tothe processor and configured to provide a first voltage and a secondvoltage; and a memory system connected to the processor and configuredto provide information to the processor, comprising: a memory; and asupply regulation circuit connected to the supply and having a regulatedvoltage connected to the memory, comprising: a reference voltage circuitconfigured to provide a control reference voltage; a control circuitconnected to the control reference voltage and configured to provide acontrol signal according to the control reference voltage; and anadjustment circuit controlled by the control signal and configured to:receive the first voltage and second voltage; generate the regulatedvoltage from at least one of the first voltage and the second voltage;and adjust the regulated voltage according to the control signal.
 2. Anelectronic system according to claim 1, wherein the second voltage is abulk voltage.
 3. An electronic system according to claim 1, wherein thereference voltage circuit comprises an adjustable impedance configuredto adjust the control reference voltage.
 4. An electronic systemaccording to claim 1, wherein the reference voltage circuit comprisesmore than one tap, wherein each tap is configured to provide acorresponding control reference voltage.
 5. An electronic systemaccording to claim 1, wherein the control circuit includes adifferential amplifier, including: a first input connected to thecontrol reference voltage; a second input connected to the regulatedvoltage; and a control signal output connected to the adjustmentcircuit.
 6. An electronic system according to claim 1, wherein thecontrol circuit is configured to generate the control signalcorresponding to a difference in magnitude between the control referencevoltage and the regulated voltage.
 7. An electronic system according toclaim 1, wherein the control circuit includes an amplifier with a gainof approximately unity.
 8. An electronic system according to claim 1,wherein the adjustment circuit comprises an impedance having anadjustable impedance value responsive to the control circuit, andwherein the regulated voltage corresponds to the adjustable impedancevalue.
 9. An electronic system according to claim 1, wherein theadjustable impedance comprises a transistor having a first terminalconnected to the regulated voltage, a second terminal connected to thesecond voltage, and a control terminal connected to the control circuit.10. An electronic system according to claim 1, further comprising acompensator circuit connected to the regulated voltage and configured toprovide a supplemental power supply to the regulated voltage.
 11. Anelectronic system according to claim 10, wherein the compensator circuitcomprises a current source connected to the regulated voltage.
 12. Anelectronic system according to claim 10, wherein the compensator circuitcomprises: a second control circuit connected to the control referencevoltage and configured to compare the regulated voltage to the controlreference voltage; and an adjustable power source responsive to thesecond control circuit and connected to the regulated voltage.
 13. Anelectronic system according to claim 10, wherein the compensator circuitcomprises a current mirror circuit.
 14. A memory system, comprising: amemory having multiple word lines and configured to use a negative wordline voltage and a supply voltage; and a supply regulation circuitconfigured to generate the negative word line voltage, wherein thesupply regulation circuit generates the negative word line voltage fromthe supply voltage.
 15. A memory system according to claim 14, whereinthe supply regulation circuit comprises: a control circuit configured togenerate a control signal corresponding to a control reference voltage;and an adjustment circuit connected to the supply voltage to dynamicallyadjust the negative word line voltage according to the control signal.16. A memory system according to claim 15, wherein the control circuitcomprises an amplifier with a gain of approximately unity.
 17. A memorysystem according to claim 15, wherein the control signal corresponds toa difference between the negative word line voltage and the controlreference voltage.
 18. A memory system according to claim 15, whereinthe adjustment circuit comprises a transistor having a control terminalconfigured to receive the control signal and a supply terminal connectedto the supply voltage.
 19. A memory system according to claim 15,wherein the adjustment circuit comprises an adjustable impedanceconnected to the supply voltage.
 20. A memory system according to claim15, wherein: the control circuit comprises a differential amplifierconfigured to compare the negative word line voltage and a controlreference voltage; and the control signal comprises a differentialoutput from the differential amplifier.
 21. A memory system according toclaim 14, further comprising a compensator circuit configured to providea current to the adjustment circuit.
 22. A memory system according toclaim 21, wherein the compensator circuit comprises a current mirrorcircuit.
 23. A memory system according to claim 14, wherein the supplyvoltage is a bulk voltage for the memory.
 24. An electronic system,comprising: a supply configured to provide a first voltage; and a supplyregulation circuit configured to provide a regulated voltage,comprising: a control circuit configured to generate a control signalaccording to the magnitude of the control reference voltage; and anadjustment circuit configured to receive the control signal and adjustthe regulated voltage according to the control signal.
 25. An electronicsystem according to claim 24, wherein the control circuit is configuredto: compare the magnitude of the control reference voltage to amagnitude of the regulated voltage; and generate the control signalaccording to the comparison of the magnitude of the control referencevoltage to the magnitude of the regulated voltage.
 26. An electronicsystem according to claim 24, wherein the control circuit includes anamplifier with a gain of approximately unity.
 27. An electronic systemaccording to claim 24, wherein the control circuit includes adifferential amplifier, including: a first input connected to thecontrol reference voltage; a second input connected to the regulatedvoltage; and a control signal output connected to the adjustmentcircuit.
 28. An electronic system according to claim 24, wherein theadjustment circuit comprises an impedance having an adjustable impedancevalue responsive to the control circuit, and wherein the regulatedvoltage corresponds to the adjustable impedance value.
 29. An electronicsystem according to claim 24, wherein the adjustable impedance comprisesa transistor, comprising: a first terminal connected to the regulatedvoltage; a second terminal connected to a reference potential; and acontrol terminal connected to the control signal.
 30. An electronicsystem according to claim 24, further comprising a compensator circuitconfigured to provide a current to the adjustment circuit.
 31. A memorysystem according to claim 24, wherein the first voltage is a bulkvoltage.
 32. A supply regulation circuit configured to generate aregulated voltage, comprising: a control circuit configured to generatea control signal according to a control reference voltage; and anadjustment circuit configured to receive the control signal and adjustthe regulated voltage according to the control signal.
 33. A supplyregulation circuit according to claim 32, wherein the control circuit isconfigured to: compare a magnitude of the control reference voltage to amagnitude of the regulated voltage; and generate the control signalaccording to the comparison of the magnitude of the control referencevoltage to the magnitude of the regulated voltage.
 34. A supplyregulation circuit according to claim 32, wherein the control circuitincludes an amplifier with a gain of approximately unity.
 35. A supplyregulation circuit according to claim 32, wherein the control circuitincludes a differential amplifier, including: a first input connected tothe control reference voltage; a second input connected to the regulatedvoltage; and a control signal output configured to provide the controlsignal.
 36. A supply regulation circuit according to claim 32, whereinthe adjustment circuit comprises an impedance having an adjustableimpedance value responsive to the control signal, and wherein theregulated voltage corresponds to the adjustable impedance value.
 37. Asupply regulation circuit according to claim 36, wherein the adjustableimpedance comprises a transistor having a first terminal connected tothe regulated voltage, a second terminal connected to a bulk voltage,and a control terminal connected to the control signal.
 38. A supplyregulation circuit according to claim 32, further comprising acompensator circuit connected to the regulated voltage and configured toprovide a supplemental power supply to the regulated voltage.
 39. Asupply regulation circuit configured to generate a negative word linevoltage, comprising: a reference voltage circuit configured to generatea control reference voltage; and an adjustment circuit configured toadjust the negative word line voltage to substantially match the controlreference voltage.
 40. A supply regulation circuit according to claim39, further comprising a control circuit configured to receive thecontrol reference voltage and the negative word line voltage, compare amagnitude of the control reference voltage to a magnitude of thenegative word line voltage, and generate a control signal according tothe comparison of the magnitude of the control reference voltage to themagnitude of the negative word line voltage; and wherein the adjustmentcircuit is configured to receive the control signal and adjust thenegative word line voltage according to the control signal.
 41. A supplyregulation circuit according to claim 40, wherein the control circuitincludes an amplifier with a gain of approximately unity.
 42. A supplyregulation circuit according to claim 40, wherein the control circuitcomprises a differential amplifier responsive to the control referencevoltage and the negative word line voltage.
 43. A supply regulationcircuit according to claim 39, wherein the adjustment circuit is furtherconfigured to provide the negative word line voltage from a supplyvoltage.
 44. A supply regulation circuit according to claim 43, whereinthe supply voltage is a bulk voltage for a memory.
 45. A supplyregulation circuit according to claim 40, wherein the adjustment circuitcomprises an adjustable impedance responsive to the control signal, andwherein the negative word line voltage corresponds to the adjustableimpedance.
 46. A supply regulation circuit according to claim 45,wherein the adjustable impedance comprises a transistor having a firstterminal connected to the negative word line voltage, a second terminalconnected to a supply voltage, and a control terminal responsive to thecontrol signal.
 47. A supply regulation circuit according to claim 40,further comprising a compensator circuit connected to the negative wordline voltage and configured to provide a supplemental power supply tothe negative word line voltage.
 48. A word line voltage supply for amemory using a word line voltage and a supply voltage, comprising: apower source configured to generate the supply voltage; a referencevoltage circuit for generating a control reference voltage; anadjustment circuit connected to the power source and configured toprovide the word line voltage from the power source at the level of thecontrol reference voltage.
 49. A word line supply according to claim 48,wherein the power source is a bulk voltage for a memory.
 50. A word linesupply according to claim 48, further comprising a control circuitconfigured to generate a control signal according to a differencebetween the control reference voltage and the word line voltage; andwherein the adjustment circuit is configured to receive the controlsignal and adjust the word line voltage according to the control signal.51. A word line supply according to claim 50, wherein the controlcircuit comprises a differential amplifier responsive to the controlreference voltage and the word line voltage.
 52. A word line supplyaccording to claim 50, wherein the control circuit comprises anamplifier with a gain of approximately unity.
 53. A word line supplyaccording to claim 48, wherein the adjustment circuit comprises anadjustable impedance, and wherein the word line voltage corresponds tothe adjustable impedance.
 54. A word line supply according to claim 53,wherein the adjustable impedance comprises a transistor having a firstterminal connected to the word line voltage, a second terminal connectedto the power source, and a control terminal responsive to the controlreference voltage.
 55. A word line supply according to claim 48, furthercomprising a compensator circuit connected to the adjustment circuit andconfigured to provide a supplemental power supply to the adjustmentcircuit.
 56. A method of providing a regulated voltage, comprising:generating a control reference voltage; comparing the regulated voltageto the control reference voltage; and adjusting the regulated voltageaccording to the comparison of the regulated voltage to the controlreference voltage.
 57. A method of providing a regulated voltageaccording to claim 56, further comprising compensating the regulatedvoltage for a power drain.
 58. A method of providing a regulated voltageaccording to claim 57, wherein compensating the regulated voltageincludes providing a current source connected to the regulated voltage.59. A method of providing a word line voltage, comprising: providing asupply voltage; providing a word line voltage from the supply voltage;providing a control reference voltage; comparing the word line voltageto the control reference voltage; and adjusting the word line voltageaccording to the comparison of the word line voltage to the controlreference voltage.